Single-pass imaging and radiation treatment delivery via an extended rotation gantry

ABSTRACT

An example method of radiation therapy in a radiation therapy system that includes a gantry with a treatment-delivering X-ray source and an imaging X-ray source mounted thereon is described. The method includes rotating the gantry in a first direction at a first rotational velocity about an open bore and concurrently rotating an annular support structure at a second rotational velocity about the open bore, wherein the second rotational velocity is less than the first rotational velocity. While continuing to rotate the gantry in the first direction about the open bore from a first position to a treatment position, the method also includes generating multiple images of a target volume disposed in the bore using the imaging X-ray source. Upon rotating the gantry to the treatment position, the method includes initiating delivery of a treatment beam to the target volume with the treatment-delivering X-ray source.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation under 35 U.S.C. § 120 of U.S.patent application Ser. No. 16,180,021, filed Nov. 5, 2018, which claimsthe benefit of U.S. Provisional Application No. 62/711,483, filed Jul.28, 2018. The aforementioned U.S. Patent Application and U.S.Provisional Application, including any appendices or attachmentsthereof, are hereby incorporated by reference in their entirety.

BACKGROUND

Unless otherwise indicated herein, the approaches described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Radiation therapy is a localized treatment for a specific target tissue,such as a cancerous tumor. Ideally, radiation therapy is performed on aplanning target volume that spares the surrounding normal tissue fromreceiving doses above specified tolerances, thereby minimizing risk ofdamage to healthy tissue. Prior to the delivery of radiation therapy, animaging system is typically employed to provide a three dimensionalimage of the target tissue and surrounding area. From such imaging, thesize and mass of the target tissue can be estimated and an appropriatetreatment plan generated and target volume determined.

So that the prescribed dose is correctly supplied to the planning targetvolume (i.e., the target tissue) during radiation therapy, the patientshould be correctly positioned relative to the linear accelerator thatprovides the radiation therapy. Typically, dosimetric and geometric dataare checked before and during the treatment, to ensure correct patientplacement and that the administered radiotherapy treatment matches thepreviously planned treatment. This process is referred to as imageguided radiation therapy (IGRT), and involves the use of an imagingsystem to view target tissues while radiation treatment is delivered tothe planning target volume. IGRT incorporates imaging coordinates fromthe treatment plan to ensure the patient is properly aligned fortreatment in the radiation therapy device.

SUMMARY

In accordance with at least some embodiments of the present disclosure,a radiation therapy system is configured to deliver radiation treatmentover a 360-degree arc and to perform a prepended imaging process, in asingle pass, via an extended rotation gantry. That is, while rotatingthe gantry in one direction about a bore of the radiation system, theradiation system generates multiple images of a target volume disposedin the bore using an imaging X-ray source mounted on the gantry. Thenwhile continuing to rotate the gantry in the same direction, theradiation system delivers a treatment beam to the target volume using atreatment-delivering X-ray source mounted on the gantry, where thetreatment beam is delivered from some or all of a 360-degree arc aboutthe bore. Thus, the prepended imaging process and the delivery ofradiation are performed in a single-pass of the gantry about a targetvolume, eliminating the need for a return stroke of the gantry forcompletion.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. These drawingsdepict only several embodiments in accordance with the disclosure andare, therefore, not to be considered limiting of its scope. Thedisclosure will be described with additional specificity and detailthrough use of the accompanying drawings.

FIG. 1 is a perspective view of a radiation therapy system, according toone or more embodiments of the present disclosure.

FIGS. 2A and 2B are schematic perspective views of the radiation therapysystem of FIG. 1, according to various embodiments of the presentdisclosure.

FIG. 3 is a schematic perspective view of a gantry of the radiationtherapy system of FIG. 1, according to various embodiments of thepresent disclosure.

FIG. 4 is a schematic perspective view of a gantry mounted on a surfaceof a drive stand, according to various embodiments of the presentdisclosure.

FIG. 5 is another schematic perspective view of a gantry mounted on asurface of a drive stand, according to various embodiments of thepresent disclosure.

FIG. 6A schematically illustrates the routing of a flexible utilityconduit when a gantry is disposed at one extent of the possible rotationof the gantry, according to an embodiment of the present disclosure.

FIG. 6B schematically illustrates the routing of a flexible utilityconduit when a gantry is disposed between the limit of clockwiserotation of the gantry and the limit of counterclockwise rotation of thegantry, according to an embodiment of the present disclosure.

FIG. 6C schematically illustrates the routing of a flexible utilityconduit when a gantry is disposed at the limit of counterclockwiserotation of the gantry, according to an embodiment of the presentdisclosure.

FIG. 7 schematically illustrates the routing of a flexible utilityconduit proximate a gantry, according to an embodiment of the presentdisclosure.

FIG. 8 schematically illustrates the routing of a flexible utilityconduit proximate a gantry, according to another embodiment of thepresent disclosure.

FIG. 9 sets forth a flowchart of an example method for radiation therapyin a radiation therapy system that includes a gantry with atreatment-delivering X-ray source and an imaging X-ray source mountedthereon, according to one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here. It will be readily understood that the aspects of thedisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, and designed in a widevariety of different configurations, all of which are explicitlycontemplated and make part of this disclosure.

In many radiation therapy systems, a volumetric arc therapy (VMAT)treatment is performed by rotating a treatment-delivering X-ray sourcethrough a 360-degree arc, so that a treatment beam can be delivered inthe plane of the X-ray source rotation from any angle. Consequently, forsuch radiation systems, the gantry on which X-ray sources are mounted istypically designed for a 360-degree rotation about the bore of thesystem. Gantry rotation of greater than about 360 degrees is generallylimited, due to interference of the liquid cooling hoses and bulky powercables coupled to the rotating gantry. As a result, any radiationtreatment that requires greater rotation of the gantry about the bore ofthe system than a single 360-degree arc can be more time consuming, andtherefore much more difficult to complete during a single breath-hold.This is because completion of a such a radiation treatment on aconventional system necessarily involves rotating the gantry through anarc to perform a first portion of the radiation treatment, stopping therotation of the gantry, performing a return stroke by rotating thegantry back to an appropriate starting location, then completing theradiation treatment by rotating the gantry to perform a final portion ofthe radiation treatment.

In image guided radiation therapy (IGRT), two- and/or three-dimensionalimaging is employed during a course of radiation treatment to improvethe accuracy of the radiation field placement, and to reduce theexposure of healthy tissue during the radiation treatment. For example,a planned radiation treatment can be adapted based on detectedintra-fraction motion and patient misalignment that may occur during thecourse of radiation treatment. Ideally, X-ray images of the treated areaare acquired immediately prior to delivery of a treatment beam andduring the same breath-hold that the treatment beam is delivered, tominimize intra-fraction motion of the treated area. For example, a conebeam computed tomography (CBCT) imaging process may be performed togenerate the X-ray images of the treated area. However, CBCT and otherprepended imaging procedures typically require rotation of the gantrythrough an arc of 90 degrees (given multiple X-ray imagers) to 180degrees (given a single X-ray imager). Further, the delivery of thetreatment beam generally requires an additional 360 degrees of gantryrotation. As a result, a gantry rotation of much more than 360 degreesis necessary to acquire X-ray images immediately prior to delivery ofthe treatment beam and during the same breath-hold. As set forth above,in conventional radiation systems, interference of the liquid coolinghoses and power cables coupled to the gantry typically occurs for gantryrotations of more than 360 degrees, thereby preventing conventionalsystems from performing such procedures in a single pass or stroke ofthe gantry.

In light of the above, there is a need in the art for improved systemsand techniques for acquiring X-ray images and delivering of a treatmentbeam during a single patient breath-hold. According to embodiments ofthe present disclosure, a radiation therapy system is configured todeliver radiation treatment throughout a 360-degree arc and to perform aprepended imaging process, in a single pass, via an extended rotationgantry. One such embodiment is illustrated if FIG. 1.

FIG. 1 is a perspective view of a radiation therapy system 100,according to one or more embodiments of the present disclosure.Radiation therapy (RT) system 100 is configured to provide stereotacticradiosurgery and precision radiotherapy for lesions, tumors, andconditions anywhere in the body where radiation treatment is indicated.As such, RT system 100 can include one or more of a linear accelerator(LINAC) that generates a megavolt (MV) treatment beam of high energyX-rays, a kilovolt (kV) X-ray source, an X-ray imager, and, in someembodiments, an MV electronic portal imaging device (EPID) (not shownfor clarity).

Generally, RT system 100 is capable of Megavolt (MV) and kilovolt (kV)imaging techniques, to enable the treatment planner and physician tomake clinical decisions that are most appropriate for the patient basedon the anatomy of the patient. In some situations, a treatment plan caninclude kV imaging for improved visualization of soft tissue. Forexample, in some embodiments, RT system 100 is configured with cone beamcomputed tomography (CBCT) capability for visualization of soft tissuevia kV images.

RT system 100 includes one or more touchscreens 101, couch motioncontrols 102, an open bore 103, a base positioning assembly 105, a couch107 disposed on base positioning assembly 105, and an image acquisitionand treatment control computer 106, all of which are disposed within atreatment room. Alternatively, in some embodiments, image acquisitionand treatment control computer 106 is located outside the treatmentroom, such as a control room adjacent to the treatment room. RT system100 further includes a remote control console 110, which is disposedoutside the treatment room and enables treatment delivery and patientmonitoring from a remote location. In some embodiments, RT system 100further includes one or more cameras (not shown) in the treatment roomfor patient monitoring.

Base positioning assembly 105 is configured to precisely position couch107 with respect to bore 103. Motion controls 102 include input devices,such as buttons and/or switches, that enable a user to operate basepositioning assembly 105 to automatically and precisely position couch107 to a predetermined location with respect to bore 103. Motioncontrols 102 may also enable a user to manually position couch 107 to aspecific location. Generally, base positioning assembly 105 isconfigured to position a patient on couch 107 so that a target region ofthe patient is at or near an isocenter about which the LINAC, EPID, kVX-ray source, and X-ray imager are rotated during RT treatment. Used inconjunction with anatomical imaging of the patient on the day oftreatment, base positioning assembly 105 can adapt a treatment plan tominimize delivered dose error due to inter-fraction motion, whichincludes the observable changes in patient anatomy that can occurbetween daily patient scans. However, intra-fraction motion, which cansignificantly impact the outcomes of radiation treatment, can be morechallenging to account for, and can result in under-dosing of the targetand/or over-dosing of organs at risk. Intra-fraction motion includesanatomical variation due to periodic motion, such as respiratory orcardiac rhythm, or episodic motion (peristalsis, muscle relaxation,cough, involuntary movement, and the like), and can only be partiallymanaged in conventional radiation therapy systems. For example, passiveimmobilization techniques can be employed, such as vac-lock bags,cradles, arm positioning handles, abdominal compression bars, etc., butthese approaches have limited effectiveness. According to embodiments ofthe present disclosure, active motion tracking of and compensation forintra-fraction motion is facilitated by performing radiation treatmentand prepended image acquisition during a single breath-hold in a singlepass of an extended rotation gantry. One such embodiment is describedbelow in conjunction with FIGS. 2A, 2B, 3, 4, 5, 6, and 7.

FIGS. 2A and 2B are schematic perspective views of RT system 100,according to various embodiments of the present disclosure. Variouselements of RT system 100 are not shown in FIGS. 2A and 2B for clarity,including a rotatable gantry, system covers, cooling systems, and thelike. As shown, RT system 100 includes a drive stand 210, a gantrybearing 220 disposed on a surface 201 of drive stand 210 and positionedaround bore 103, and a force coil array 230 disposed on surface 211.Drive stand 210 is a fixed support structure for components of RT system100, including a gantry, cooling systems of RT system 100, displayscreens, control electronics, and the like. Drive stand 210 rests onand/or is fixed to a support surface 202 that is external to RT system100, such as a floor of an RT treatment facility. Gantry bearing 220rotatably supports the gantry of RT system 100, and force coil array 230includes a plurality of forcing coils 231 that cause the gantry torotate. In some embodiments, forcing coils 231 are controlled by imageacquisition and treatment control computer 106 in FIG. 1 to causerotation of the gantry. Specifically, forcing coils 231, when properlyenergized, exert pushing or pulling forces on magnets coupled to thegantry.

FIG. 3 is a schematic perspective view of a gantry 300 of RT system 100,according to various embodiments of the present disclosure. Gantry 300is a rotatable support structure on which components 340 are mounted.Components 340 include systems and devices of RT system 100 that arerotated about bore 103 during RT treatment. Components 340 includeheat-generating systems and/or electrically powered systems, such as aLINAC, EPID, kV X-ray source, and/or X-ray imager. Gantry 300 includes aplurality of magnets 301, such as permanent magnets, affixed to asurface 302 that faces surface 201 of drive stand 210 (shown in FIG.2B). Magnets 301 interact with forcing coils 231 of force coil array 230(shown in FIG. 2B) to cause rotation of gantry 300. In some embodiments,gantry 300 further includes a conduit management surface 303 on whichone or more flexible utility conduits (not shown) are collected orretrieved from as gantry 300 rotates from one rotational position toanother rotational position. In some embodiments, gantry 300 furtherincludes a gantry flange 304 that prevents flexible utility conduitscollected on conduit management surface 303 from being displaced off ofconduit management surface 303 during rotation of gantry 300. Suchflexible utility conduits, and the interactions thereof with conduitmanagement surface 303, are described below in conjunction with FIGS. 4,5, 6A, 6B, and 6C.

FIG. 4 is a schematic perspective view of gantry 300 mounted on surface201 of drive stand 210, according to various embodiments of the presentdisclosure. Force coil array 230 (see FIG. 2B) and conduit managementsurface 303 (see FIG. 3) are obscured in FIG. 4 by gantry flange 304.According to embodiments of the present disclosure, gantry 300 isconfigured to rotate continuously in a single direction through an arcthat is significantly greater than 360 degrees, for example 480 degrees,540 degrees, or the like. Thus, gantry 300 enables acquiring X-rayimages and delivery of a treatment beam during a single pass (or stroke)of gantry 300. As a result, completing acquisition of X-ray images andthe subsequent delivery of a treatment beam during a single patientbreath-hold is greatly facilitated.

FIG. 5 is another schematic perspective view of gantry 300 mounted onsurface 201 of drive stand 210, according to various embodiments of thepresent disclosure. In FIG. 5, gantry flange 304 is not shown, so thatconduit management surface 303 and an annular support structure 501(solid) are visible. A guide wheel 502 is mounted on annular supportstructure 501, and a flexible utility conduit 503 is coupled to guidewheel 502 and is also visible.

Like gantry 300, annular support structure 501 is rotatably coupled todrive stand 210, and is configured to rotate about bore 103 of RT system100 during radiation treatment. More specifically, annular supportstructure 501 is configured to rotate in the same direction that gantry300 rotates about bore 301, but at half the rotational velocity. Forexample, when gantry 300 rotates clockwise about bore 301 at 4 RPM,annular support structure 501 is configured to rotate clockwise (orcounterclockwise) about bore 301 at 2 at RPM. Similarly, when gantry 300rotates counterclockwise about bore 301 at a certain rotationalvelocity, annular support structure 501 is configured to rotatecounterclockwise about bore 301 at one half that rotational velocity.Furthermore, annular support structure 501 is configured to support androtationally displace guide wheel 502. That is, as annular supportstructure 501 rotates about bore 103, guide wheel 502 is displacerotationally about bore 103.

Guide wheel 502 is a rotatable conduit management cylinder that isrotatably coupled to annular support structure 501. Guide wheel 502 isconfigured to guide flexible utility conduit 503 (dashed line) from afixed connection point on drive stand 210 to a fixed connection point ongantry 300. More specifically, flexible utility conduit 503 is routedfrom the fixed connection point on drive stand 210, around guide wheel502 for one-half turn, along conduit management surface 303 of gantry300, to the fixed connection point on gantry 300.

Flexible utility conduit 503 includes one or more hoses for coolingliquid and/or power cables (radio frequency, alternating current, directcurrent, and the like). Flexible utility conduit 503 can be a singlehose or power cable, or a bundle of multiple hoses and/or power cables.Thus, flexible utility conduit 503 routes one or more utilities fromdrive stand 210 to gantry 300. One end of flexible utility conduit 503is coupled to a connector 512 mounted on drive stand 210, which remainsmotionless during operation of RT system 100. In addition, an oppositeend of flexible utility conduit 503 is coupled to a connector 522mounted on gantry 300, which does not remain motionless during operationof RT system 100. Instead, connector 522 is rotationally displaced aboutbore 103 as gantry 300 rotates about bore 103. As is evident from FIG.5, if flexible utility conduit 503 were routed directly to connector 522from connector 512, instead of being routed around guide wheel 502,rotation of gantry 300 of greater than about 360 degrees is likely tocause fouling of flexible utility conduit 503 and/or interference withrotation of gantry 300. However, according to embodiments of the presentdisclosure, flexible utility conduit 503 is routed to connector 522 fromconnector 512 via guide wheel 502, which rotationally translates aboutbore 103 when gantry 300 rotates about bore 103. As a result, gantry 300can rotate continuously in a single direction through an arc that issignificantly greater than 360 degrees, for example 480 degrees or 540degrees, without interference from flexible utility conduit 503. Onesuch embodiment is illustrated in FIGS. 6A, 6B, and 6C.

FIG. 6A schematically illustrates the routing of flexible utilityconduit 503 when gantry 300 is radially oriented at one extent of thepossible rotation of gantry 300, according to an embodiment of thepresent disclosure. In FIG. 6A, gantry 300 is rotated to the limit ofclockwise rotation for gantry 300 and annular support structure 501 isat the limit of clockwise rotation for annular support structure 501. Asa result, annular support structure 501 (solid) is oriented so thatguide wheel 502 (which is mounted on annular support structure 501) isdisposed radially proximate connector 522 (which is mounted on gantry300). Flexible utility conduit 503 is routed for approximately one-halfturn around guide wheel 502. In the embodiment illustrated in FIG. 6A,connector 512, which is mounted on drive stand 210, is radiallydisplaced (counterclockwise) from guide wheel 502 by approximately 225degrees when gantry 300 is at the maximum extent of clockwise rotationshown in FIG. 6A. In other embodiments, connector 512 can be mounted ondrive stand 210 at a location that is radially displaced from guidewheel 502 by as much as about 350 degrees.

FIG. 6B schematically illustrates the routing of flexible utilityconduit 503 when gantry 300 is disposed between the limit of clockwiserotation of gantry 300 and the limit of counterclockwise rotation ofgantry 300, according to an embodiment of the present disclosure. InFIG. 6B, gantry 300 has rotated counterclockwise 270 degrees from theposition shown in FIG. 6A. As a result, annular support structure 501,which is configured to rotate in the same direction as gantry 300 but athalf the rotational velocity, is oriented so that guide wheel 502 isradially disposed at about halfway between the current radial locationof connector 522 if FIG. 6B and the original radial location ofconnector 522, shown in FIG. 6A.

FIG. 6C schematically illustrates the routing of flexible utilityconduit 503 when gantry 300 is disposed at the limit of counterclockwiserotation of gantry 300, according to an embodiment of the presentdisclosure. In FIG. 6C, gantry 300 has rotated counterclockwise anadditional 270 degrees from the position shown in FIG. 6B, and is at thelimit of counterclockwise rotation for gantry 300. Annular supportstructure 501 rotated counterclockwise an additional 135 degrees, and isat the limit of counterclockwise rotation for annular support structure501. As a result, annular support structure 501 is oriented so thatguide wheel 502 (which is mounted on annular support structure 501) isdisposed radially proximate connector 512 (which is mounted on drivestand 210).

As illustrated in FIGS. 6A, 6B, and 6C, flexible utility conduit 503 isrouted for a half-turn around guide wheel 502, and guide wheel 502 isrotationally displaced in the same direct that gantry 300 is displaced.Consequently, when gantry 300 rotates during operation, a “wind-up”action is effectuated with respect to flexible utility conduit 503. Thatis, when gantry 300 is rotated to cause connector 522 to move towardconnector 512, slack in flexible utility conduit 503 that would normallybe generated is instead drawn across conduit management surface 303. Asa result, gantry 300 can rotate in a single direction through an arcgreater than 360 and up to approximately 700 degrees without the risk ofslack loops of flexible utility conduit 503 catching on portions ofgantry 300 or drive stand 210, or otherwise interfering with motion ofgantry 300.

In the embodiment illustrated in FIGS. 6A, 6B, and 6C, a single guidewheel 502 is coupled to annular support structure 501, and a singleflexible utility conduit 503 is guided from a fixed connection point ondrive stand 210 to a fixed connection point on gantry 300 via guidewheel 502. In other embodiments, multiple flexible utility conduits areeach guided from a respective fixed connection point on drive stand 210to a respective fixed connection point on gantry 300 via a respectiveguide wheel. Thus, in such embodiments, multiple guide wheels arerotatably mounted on annular support structure 501.

In some instances, different portions of flexible utility conduit 503can come in contact with each other during rotation of gantry 300. Onesuch instance in depicted in FIG. 6B, in which a portion of flexibleutility conduit 503 leading from connector 512 contacts a portion offlexible utility conduit 503 disposed on conduit management surface 303of gantry 300. These contacting portions of flexible utility conduit 503are moving relative to each other, since conduit management surface 303is rotating past the portion of flexible utility conduit 503 leadingfrom connector 512. Thus, surfaces of flexible utility conduit 503 canundergo additional wear during use. According to some embodiments of thepresent disclosure, RT system 100 includes one or more cable separatorsto prevent such wear. One such embodiment is illustrated in FIG. 7 andanother is illustrated in FIG. 8.

FIG. 7 schematically illustrates the routing of flexible utility conduit503 proximate gantry 300, according to an embodiment of the presentdisclosure. In the embodiment illustrated in FIG. 7, RT 100 includes oneor more separating wheels 701, which are rotatably coupled to annularsupport structure 501 as shown. Thus, separating wheels 701 arepositioned between a portion of flexible utility conduit 503 that isdisposed against conduit management surface 303 and a portion offlexible utility conduit 503 that leads from guide wheel 502 toconnector 512. As a result, flexible utility conduit 503 undergoes lesswear during rotation of gantry 300.

FIG. 8 schematically illustrates the routing of flexible utility conduit503 proximate gantry 300, according to another embodiment of the presentdisclosure. In the embodiment illustrated in FIG. 8, RT 100 includes oneor more electromagnets 801, which are fixed to a static (non-rotating)surface of drive stand 210. In addition, a flexible utility conduit 803is configured with one or more ferromagnetic plates 802. As shown,ferromagnetic plates 802 are coupled to an outer surface 804 of flexibleutility conduit 803. In some embodiments, flexible utility conduit 803is configured with a rectangular cross-section, which facilitates thecoupling of ferromagnetic plates 802 to outer surface 804. In suchembodiments, a computing device, such as image acquisition and treatmentcontrol computer 106, can be configured to energize and de-energizeelectromagnets 801 with appropriate timing, so that a portion offlexible utility conduit 803 that leads from guide wheel 502 toconnector 512 is held away from a portion of flexible utility conduit503 that is disposed against conduit management surface 303.

FIG. 9 sets forth a flowchart of an example method for radiation therapyin a radiation therapy system that includes a gantry with atreatment-delivering X-ray source and an imaging X-ray source mountedthereon, according to one or more embodiments of the present disclosure.The method may include one or more operations, functions, or actions asillustrated by one or more of blocks 901-911. Although the blocks areillustrated in a sequential order, these blocks may be performed inparallel, and/or in a different order than those described herein. Also,the various blocks may be combined into fewer blocks, divided intoadditional blocks, and/or eliminated based upon the desiredimplementation. Although the method is described in conjunction with thesystems of FIGS. 1-8, persons skilled in the art will understand thatany suitably configured radiation therapy system is within the scope ofthe present disclosure.

A method 900 begins at step 901, in which a computing device associatedwith RT system 100 (such as image acquisition and treatment controlcomputer 106) causes gantry 300 to rotationally accelerate about bore103 from no rotational velocity to a target rotational velocity whilerotating in a specific direction (e.g., either clockwise orcounterclockwise). In some embodiments, step 901 is synchronized with orinitiated in response to the start of a patient breath-hold. In step901, the gantry begins to rotationally accelerate from a start position,such as a radial position that is proximate one extent of the possiblerotation of gantry 300. The acceleration may be constant or may bevariable, such as an S-curve acceleration profile for reducing oreliminating jerk when reaching a target acceleration or deceleration.Generally, the rotational acceleration of gantry 300 ends when a targetrotational velocity is achieved by gantry 300 and/or gantry 300 reachesa certain rotational location, such as an imaging position. In someembodiments, the target rotational velocity is reached after 5-20degrees of rotation of gantry 300.

In step 902, while causing gantry 300 to continue rotating in the samedirection as the rotational acceleration described in step 901, from theimaging position to a treatment position, the computing device causesmultiple images of a target volume disposed in bore 103 to be generatedusing an imaging X-ray source of RT system 100. For example, in someembodiments, the target volume is a region surrounding and including aspecific target tissue (a planning target volume), such as a canceroustumor. In some embodiments, the generated images are projection imagesof the planning target volume. In some embodiments, the treatmentposition is separated from the first position in the current directionof rotation of gantry 300 by at least about one quarter rotation, or 90degrees, of gantry 300.

In step 903, the computing device determines whether the currentdelivery of the treatment beam should be modified, based on the multipleimages of the planning target volume generated in step 902. In someembodiments, a current position of the planning target volume can bedetermined based on the multiple images, for example, by performingdigital tomosynthesis on the projection images generated in step 902.The current position can then be compared to a predicted position of theplanning target volume, and position error of the planning target volumequantified. If the computing device determines that the current deliveryof the treatment beam should be modified, method 900 proceeds to step911; if not, method 900 proceeds to step 904. In some embodiments,modification of the treatment beam includes aborting the currenttreatment under certain conditions.

In step 904, the computing device causes gantry 300 to continue torotate through the treatment position, and causes delivery of atreatment beam to the planning target volume to be initiated with atreatment-delivering X-ray source of RT system 100. In some embodiments,the computing device then causes the treatment to continue to bedelivered until gantry 300 has completed a full revolution, i.e., a360-degree arc from the treatment position to the treatment position. Inembodiments in which the delivery of the treatment beam has beenmodified (see step 911), the computing device causes the modifiedtreatment to be implemented in step 904. In yet another embodiment, a kVimaging process is interleaved with the delivery of the treatment beam,and as the treatment arc proceeds, images are continuously beingupdated, thereby checking that the planning target volume has not movedduring the current breath-hold. In such embodiments, when the planningtarget volume has been determined to have moved beyond a thresholddisplacement, the computing device turns off the treatment beam. It isnoted that, after gantry 300 has rotated past the treatment position,imaging can also take place and not just delivery of the treatment beam.

In step 905, after gantry 300 has completed the revolution from thetreatment position to the treatment position, the computing devicecauses gantry 300 to rotationally decelerate from the target rotationalvelocity to no rotational velocity. The deceleration takes place whilegantry 300 rotates in the current rotational direction from thetreatment position to a stopping position. In some embodiments, thestopping position is radially proximate another extent of the possiblerotation of gantry 300. In some embodiments, no rotational velocity isreached from the target rotational velocity after 5-20 degrees ofrotation of gantry 300.

In step 906, after rotationally decelerating gantry 300 from the targetrotational velocity to no rotational velocity, rotating gantry 300 in asecond direction to the start position, where the second direction isopposite to the specific direction. That is, the computing device causesgantry 300 to rotate back to the start position described in step 901.

In step 911, which is performed in response to the computing devicedetermining that the treatment beam should be modified, the computingdevice determines a modified delivery of the treatment beam, or abortsthis attempt and the patient is asked to re-start a breath-hold with adifferent amount of air. In some embodiments, the modified delivery isbased on the images generated in step 902.

Implementation of method 900 as described above enables radiationtreatment and prepended image acquisition in a single pass of anextended-rotation gantry. Such radiation treatment can be more readilyperformed during a single breath-hold by a patient, thereby maximizingthe number of patients who are able to undergo the radiation treatment.

The descriptions of the various embodiments have been presented forpurposes of illustration, but are not intended to be exhaustive orlimited to the embodiments disclosed. Many modifications and variationswill be apparent to those of ordinary skill in the art without departingfrom the scope and spirit of the described embodiments.

Aspects of the present embodiments may be embodied as a system, methodor computer program product. Accordingly, aspects of the presentdisclosure may take the form of an entirely hardware embodiment, anentirely software embodiment (including firmware, resident software,micro-code, etc.) or an embodiment combining software and hardwareaspects that may all generally be referred to herein as a “circuit,”“module” or “system.” Furthermore, aspects of the present disclosure maytake the form of a computer program product embodied in one or morecomputer readable medium(s) having computer readable program codeembodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

We claim:
 1. A computer-implemented method of radiation therapy in aradiation therapy system that includes a gantry with atreatment-delivering X-ray source and an imaging X-ray source mountedthereon, the method comprising: rotating the gantry in a first directionat a first rotational velocity about an open bore and concurrentlyrotating an annular support structure at a second rotational velocityabout the open bore, wherein the second rotational velocity is less thanthe first rotational velocity; while continuing to rotate the gantry inthe first direction about the open bore from a first position to atreatment position, generating multiple images of a target volumedisposed in the bore using the imaging X-ray source; and upon rotatingthe gantry to the treatment position, initiating delivery of a treatmentbeam to the target volume with the treatment-delivering X-ray source. 2.The computer-implemented method of claim 1, wherein rotating the gantryin the first direction at the first rotational velocity about the openbore comprises rotating the gantry in the first direction while a firstend of a flexible utility conduit is coupled to the treatment-deliveringX-ray source and a second end of the flexible utility conduit is coupledto a fixed support structure of the radiation therapy system that isrotatably coupled to the gantry.
 3. The computer-implemented method ofclaim 1, further comprising, while rotating the gantry in the firstdirection at the first rotational velocity about the open bore andconcurrently rotating the annular support structure at the secondrotational velocity about the open bore, energizing an electromagnetthat is coupled to a non-rotating surface of the drive stand and isconfigured to separate a first portion of the flexible utility conduitfrom a second portion of the flexible utility conduit during rotation ofthe gantry.
 4. The computer-implemented method of claim 1, wherein theannular support structure includes a conduit management cylinder that iscoupled to the annular support structure and is configured to guide theflexible utility conduit from the fixed connection on the drive stand tothe fixed connection on the gantry.
 5. The computer-implemented methodof claim 1, wherein the second rotational velocity is one half than thefirst rotational velocity.
 6. The computer-implemented method of claim1, further comprising, while continuing to rotate the gantry in thefirst direction from the treatment position, interleaving an imagingprocess with the delivery of the treatment beam.
 7. A radiationtreatment system comprising: a drive stand; a gantry with atreatment-delivering X-ray source mounted thereon, wherein the gantry isrotatably coupled to the drive stand and is configured to rotate in afirst direction about a bore of the radiation treatment system at afirst rotational velocity; an annular support structure that isrotatably coupled to the drive stand and is configured to rotate in thefirst direction about the bore of the radiation treatment system at asecond rotational velocity when the gantry rotates about the bore at thefirst rotational velocity, wherein the second rotational velocity isless than the first rotational velocity; and a processor configured to:cause the gantry to rotate in the first direction about the bore from atreatment position at the first rotational velocity and concurrentlycause the annular support structure to rotate in the first directionabout the bore at the second rotational velocity; and while causing thegantry to rotate in the first direction about the bore from thetreatment position, initiate delivery of a treatment beam to a targetvolume disposed in the bore using with the treatment-delivering X-raysource.
 8. The radiation treatment system of claim 7, further comprisinga flexible utility conduit with a first end that is coupled to a fixedconnection on the drive stand and a second end that is coupled to afixed connection on the gantry.
 9. The radiation treatment system ofclaim 8, wherein the annular support structure includes a conduitmanagement cylinder that is coupled to the annular support structure andis configured to guide the flexible utility conduit from the fixedconnection on the drive stand to the fixed connection on the gantry. 10.The radiation treatment system of claim 9, wherein the conduitmanagement cylinder is rotatably coupled to the annular supportstructure.
 11. The radiation treatment system of claim 9, wherein theconduit management cylinder is configured to guide the flexible utilityconduit from the fixed connection on the drive stand to the fixedconnection on the gantry during rotation of the annular supportstructure.
 12. The radiation treatment system of claim 9, wherein theflexible utility conduit is routed for one-half turn around the conduitmanagement cylinder.
 13. The radiation treatment system of claim 8,further comprising at least one cable separator that is coupled to theannular support structure and is configured to separate a first portionof the flexible utility conduit from a second portion of the flexibleutility conduit during rotation of the gantry.
 14. The radiationtreatment system of claim 13, wherein the at least one cable separatoris rotatably coupled to the annular support structure.
 15. The radiationtreatment system of claim 13, wherein the at least one cable separatoris positioned between a portion of the flexible utility conduit thatleads from a conduit management cylinder coupled to the annular supportstructure to the fixed connection on the drive stand and a portion ofthe flexible utility conduit that is disposed against a conduitmanagement surface of a conduit management cylinder.
 16. The radiationtreatment system of claim 8, further comprising at least one cableseparator that is coupled to a non-rotating surface of the drive standand is configured to separate a first portion of the flexible utilityconduit from a second portion of the flexible utility conduit duringrotation of the gantry.
 17. The radiation treatment system of claim 16,wherein the at least one cable separator includes an electromagnet thatis configured to, when energized, attract a ferromagnetic plate that iscoupled to the flexible utility conduit and separate a first portion ofthe flexible utility conduit from a second portion of the flexibleutility conduit during rotation of the gantry
 18. The radiationtreatment system of claim 17, wherein the ferromagnetic plate ispositioned on the non-rotating surface of the drive to align with theferromagnetic plate coupled to the flexible utility conduit duringrotation of the gantry.
 19. The radiation treatment system of claim 8,further comprising an imaging X-ray source mounted on the gantry. 20.The radiation treatment system of claim 19, wherein the processor isfurther configured to generate an image of the target volume using theimaging X-ray source while causing the gantry to rotate in the firstdirection.